<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.10/dist/vue.js"></script>
</head>

<body>
    <div id="app">
        <h1>全名：{{fullName}}</h1>
    </div>
    <script>
        Vue.config.productionTip = false;
        // 使用watch来书写获取全名的逻辑，感受watch和computed的区别
        const vm = new Vue({
            el: "#app",
            data() {
                return {
                    firstName:"奥",
                    lastName:"特曼",
                    fullName:"",
                }
            },
            watch:{
                firstName:{
                    // 立即监听
                    immediate:true,
                    handler(){
                        this.fullName =this.firstName.toLowerCase()+" "+this.lastName.toLowerCase();
                    }
                },
                lastName:{
                    immediate:true,
                    handler(){
                        this.fullName =this.firstName.toLowerCase()+" "+this.lastName.toLowerCase();

                    }
                }
            }
        })
</script>
</body>

</html>